1. Field of the Invention
The present invention relates to a novel polymerizable compound which is useful for optical materials such as optical fibers and optical waveguides, optical disc substrates and photoresists and raw materials thereof, pharmaceutical or agricultural intermediates and raw materials of polymer compounds to be used for other various industrial products and so on and to a polymer compound obtained by using the same. Also, the invention relates to a novel polymerizable compound which is useful for raw materials of polymer compounds to be used for chemical amplification type resist materials for KrF, ArF or F2 excimer lasers, chemical amplification type resist materials for ArF liquid immersion exposure and chemical amplification type resist materials for X-rays, electron beams or EUV (extreme ultraviolet rays) and to a polymer compound obtained by using the same.
2. Description of the Related Art
In chemical amplification resists, an acid is generated in an exposed area upon irradiation with radial rays such as far ultraviolet rays, and the solubility in a developing solution is changed between an exposed area and an unexposed area with active radial rays due to a reaction using this acid as a catalyst, thereby forming a pattern on a substrate.
In the case where a KrF excimer laser is used as an exposure light source, resins having poly(hydroxystyrene) as a basic skeleton, which are low in absorption chiefly in a region of 248 nm, are used as a main component, and therefore, they form a good pattern with a high sensitivity at a high resolution and become a good system as compared with related-art naphthoquinonediazide/novolak resin systems.
On the other hand, in the case where a light source with a shorter wavelength, for example, an ArF excimer laser (193 nm) is used as an exposure light source, compounds having an aromatic group display large absorption essentially in a region of 193 nm, and therefore, they were not sufficient even in the foregoing chemical amplification system. For that reason, resists for ArF excimer laser containing a resin having an alicyclic hydrocarbon structure are being developed.
Furthermore, it has been found that by incorporating a repeating unit having a lactone structure into the foregoing resin having an alicyclic hydrocarbon structure, the performance is enhanced. For example, JP-A-2006-146143 discloses a resin composition using a resin containing a repeating unit having an alicyclic lactone structure.
However, from the viewpoint of overall performance as a resist, it is the actual situation that it is extremely difficult to find out an appropriate combination of a resin, a photoacid generator, an additive, a solvent, etc. to be used. Furthermore, in forming a fine pattern with a line width of not more than 100 nm, improvements in not only a resolving power but a line edge roughness performance of line pattern were demanded.
The “line edge roughness” as referred to herein means that an edge of a resist at an interface between a line pattern and a substrate assumes a shape in which it irregularly fluctuates in a direction vertical to a line direction due to characteristics of the resist. When this pattern is observed from the top, the edge is seen unevenly (from about ±several nm to several ten nm). Such unevenness is transferred onto the substrate in an etching step, and therefore, when the unevenness is large, failure in electrical characteristics is caused, resulting in a lowering in the yield. However, this repeating unit having a lactone structure was problematic in an affinity with a developing solution.